A run on gas masks: Shoppers in Israel yesterday, loading up in the wake of strikes that may have kept chemical weapons out of terrorist hands. Photo: EPA

After sitting on the sidelines for two years of regional turmoil, the Israeli Air Force reportedly attacked military targets near the Syrian-Lebanese border in the wee hours yesterday.

Breaking long hours of silence, Syria’s government-owned media finally confirmed last night that Israel, in an act of “naked aggression,” targeted a “military research center” near Damascus.

The Syrian outlets denied (more reliable) Western media reports that the target was a convoy carrying advanced Russian-made SA-17 surface-to-air missiles from Syria to Lebanon.

Was the target Syria’s chemical arsenal, or “merely” a delivery of Syrian arms that could upgrade the Lebanese-based Hezbollah’s air defenses — or both? Either way, Jerusalem’s signal to the region is clear: The Israeli Defense Force is determined to act when well-known “red lines” are crossed.

As Syria bleeds, the West mostly wrings its hands. Briefing the UN Security Council Tuesday, Lakhdar Brahimi, the joint UN-Arab League envoy to Syria, apologized for “sounding like a broken record” as he warned diplomats about their failure to unite and act while the country disintegrates. (In lieu of action, America and other powers gathered in Kuwait yesterday, “We Are the World”-style, to raise cash for Syrian victims.)

For Israel, the stakes are too high to sit back.

Last Wednesday, a day after an Israeli election that gave him a new term in office, Prime Minister Benjamin Netanyahu unexpectedly gathered a few top officials, known as the Security Cabinet, to discuss unspecified but “growing” threats in Israel’s north.

Soon after, Israel deployed in the north, near the Syrian and Lebanon borders, two Iron Dome batteries (the anti-missile system that has proved its effectiveness in last fall’s war against Hamas in Gaza).

The IDF’s intelligence chief, Aviv Kokhavi was sent to Washington, and Netanyahu’s national security adviser, Yaakov Amidror, to Moscow to notify both powers of the pending operation.

But why now?

Jerusalem has long made it known in the region that even as the vaunted “international community” fails to stop Iran’s and Syria’s illicit arming of Hezbollah, some weapons are a definite no-no. Among them, yes, chemicals, but also advanced long-range missiles and anything that may limit Israel’s air superiority.

For years, the ruthless but calculating Damascus regime avoided violating those “red lines.” But now, as President Bashar al-Assad loses control over large swaths of the country, and some of his top generals defect to the rebels, the rules of the games are fast changing.

As unrest intensifies in Syria, Egypt and the rest of the Mideast, the risks for Israel are rising. “We must prepare to face a large array of new threats — from small to large, from knives to nukes,” Gen. Amir Eshel, the Air Force commander, told a conference near Tel Aviv this week.

Speaking of which: A story on the World Net Daily Web site this week detailed an internal explosion that purportedly destroyed much of Iran’s deeply dug facility, Fordow. (This nuclear site near the holy city of Qom has most worried IDF military planners because of its immunity to Israeli air attacks.)

Israel became quickly the top suspect in the supposed sabotage — even as Iran denied it ever happened and the Vienna-based International Atomic Energy Agency said that its inspectors in Iran saw no signs such a blast took place.

Whatever the truth of the Fordow story, it was so widely distributed that, as the Hudson Institute’s Hillel Fradkin tells me, Iran now “has an incentive to show some response” and retaliate against Israel.

(Israelis, by the way, are getting good at lowering such incentives. “No comment” is the best you get from Jerusalem officials — on either the Fordow story, or yesterday’s reported attack in Syria. Even the country’s most boastful showoffs realize that it’s best to let the other side lick its wounds privately than “force” it to retaliate.)

Either way, as Jerusalem (along with Washington) enters what’s widely considered to be a “year of decision” — let Iran become a nuclear power or act to end its program — the IDF must do its utmost to limit the capacity of Hezbollah and other Tehran allies to retaliate against Israeli population centers on behalf of the Iranian puppet masters.

And that’s why yesterday’s reported action in Syria — a first of its kind since the Arab Spring began — is unlikely to be the last.